SummaryMost hereditary diseases in humans are genetically complex, resulting from combinations of mutations in multiple genes. However synthetic interactions between genes are very difficult to identify in population studies because of a lack of statistical power and we fundamentally do not understand how mutations interact to produce phenotypes. C. elegans is a unique animal in which genetic interactions can be rapidly identified in vivo using RNA interference, and we recently used this system to construct the first genetic interaction network for any animal, focused on signal transduction genes. The first objective of this proposal is to extend this work and map a comprehensive genetic interaction network for this model metazoan. This project will provide the first insights into the global properties of animal genetic interaction networks, and a comprehensive view of the functional relationships between genes in an animal. The second objective of the proposal is to use C. elegans to develop and validate experimentally integrated gene networks that connect genes to phenotypes and predict genetic interactions on a genome-wide scale. The methods that we develop and validate in C. elegans will then be applied to predict phenotypes and interactions for human genes. The final objective is to dissect the molecular mechanisms underlying genetic interactions, and to understand how these interactions evolve. The combined aim of these three objectives is to generate a framework for understanding and predicting how mutations interact to produce phenotypes, including in human disease.

Most hereditary diseases in humans are genetically complex, resulting from combinations of mutations in multiple genes. However synthetic interactions between genes are very difficult to identify in population studies because of a lack of statistical power and we fundamentally do not understand how mutations interact to produce phenotypes. C. elegans is a unique animal in which genetic interactions can be rapidly identified in vivo using RNA interference, and we recently used this system to construct the first genetic interaction network for any animal, focused on signal transduction genes. The first objective of this proposal is to extend this work and map a comprehensive genetic interaction network for this model metazoan. This project will provide the first insights into the global properties of animal genetic interaction networks, and a comprehensive view of the functional relationships between genes in an animal. The second objective of the proposal is to use C. elegans to develop and validate experimentally integrated gene networks that connect genes to phenotypes and predict genetic interactions on a genome-wide scale. The methods that we develop and validate in C. elegans will then be applied to predict phenotypes and interactions for human genes. The final objective is to dissect the molecular mechanisms underlying genetic interactions, and to understand how these interactions evolve. The combined aim of these three objectives is to generate a framework for understanding and predicting how mutations interact to produce phenotypes, including in human disease.

Max ERC Funding

1 100 000 €

Duration

Start date: 2008-09-01, End date: 2014-04-30

Project acronym3D_Tryps

ProjectThe role of three-dimensional genome architecture in antigenic variation

Researcher (PI)Tim Nicolai SIEGEL

Host Institution (HI)LUDWIG-MAXIMILIANS-UNIVERSITAET MUENCHEN

Call DetailsStarting Grant (StG), LS6, ERC-2016-STG

SummaryAntigenic variation is a widely employed strategy to evade the host immune response. It has similar functional requirements even in evolutionarily divergent pathogens. These include the mutually exclusive expression of antigens and the periodic, nonrandom switching in the expression of different antigens during the course of an infection. Despite decades of research the mechanisms of antigenic variation are not fully understood in any organism.
The recent development of high-throughput sequencing-based assays to probe the 3D genome architecture (Hi-C) has revealed the importance of the spatial organization of DNA inside the nucleus. 3D genome architecture plays a critical role in the regulation of mutually exclusive gene expression and the frequency of translocation between different genomic loci in many eukaryotes. Thus, genome architecture may also be a key regulator of antigenic variation, yet the causal links between genome architecture and the expression of antigens have not been studied systematically. In addition, the development of CRISPR-Cas9-based approaches to perform nucleotide-specific genome editing has opened unprecedented opportunities to study the influence of DNA sequence elements on the spatial organization of DNA and how this impacts antigen expression.
I have adapted both Hi-C and CRISPR-Cas9 technology to the protozoan parasite Trypanosoma brucei, one of the most important model organisms to study antigenic variation. These techniques will enable me to bridge the field of antigenic variation research with that of genome architecture. I will perform the first systematic analysis of the role of genome architecture in the mutually exclusive and hierarchical expression of antigens in any pathogen.
The experiments outlined in this proposal will provide new insight, facilitating a new view of antigenic variation and may eventually help medical intervention in T. brucei and in other pathogens relying on antigenic variation for their survival.

Antigenic variation is a widely employed strategy to evade the host immune response. It has similar functional requirements even in evolutionarily divergent pathogens. These include the mutually exclusive expression of antigens and the periodic, nonrandom switching in the expression of different antigens during the course of an infection. Despite decades of research the mechanisms of antigenic variation are not fully understood in any organism.
The recent development of high-throughput sequencing-based assays to probe the 3D genome architecture (Hi-C) has revealed the importance of the spatial organization of DNA inside the nucleus. 3D genome architecture plays a critical role in the regulation of mutually exclusive gene expression and the frequency of translocation between different genomic loci in many eukaryotes. Thus, genome architecture may also be a key regulator of antigenic variation, yet the causal links between genome architecture and the expression of antigens have not been studied systematically. In addition, the development of CRISPR-Cas9-based approaches to perform nucleotide-specific genome editing has opened unprecedented opportunities to study the influence of DNA sequence elements on the spatial organization of DNA and how this impacts antigen expression.
I have adapted both Hi-C and CRISPR-Cas9 technology to the protozoan parasite Trypanosoma brucei, one of the most important model organisms to study antigenic variation. These techniques will enable me to bridge the field of antigenic variation research with that of genome architecture. I will perform the first systematic analysis of the role of genome architecture in the mutually exclusive and hierarchical expression of antigens in any pathogen.
The experiments outlined in this proposal will provide new insight, facilitating a new view of antigenic variation and may eventually help medical intervention in T. brucei and in other pathogens relying on antigenic variation for their survival.

SummaryThis proposal brings together two fields in biology, namely the emerging field of phase-separated assemblies in cell biology and state-of-the-art cellular cryo-electron tomography, to advance our understanding on a fundamental, yet illusive, question: the molecular organization of the cytoplasm.
Eukaryotes organize their biochemical reactions into functionally distinct compartments. Intriguingly, many, if not most, cellular compartments are not membrane enclosed. Rather, they assemble dynamically by phase separation, typically triggered upon a specific event. Despite significant progress on reconstituting such liquid-like assemblies in vitro, we lack information as to whether these compartments in vivo are indeed amorphous liquids, or whether they exhibit structural features such as gels or fibers. My recent work on sample preparation of cells for cryo-electron tomography, including cryo-focused ion beam thinning, guided by 3D correlative fluorescence microscopy, shows that we can now prepare site-specific ‘electron-transparent windows’ in suitable eukaryotic systems, which allow direct examination of structural features of cellular compartments in their cellular context. Here, we will use these techniques to elucidate the structural principles and cytoplasmic environment driving the dynamic assembly of two phase-separated compartments: Stress granules, which are RNA bodies that form rapidly in the cytoplasm upon cellular stress, and centrosomes, which are sites of microtubule nucleation. We will combine these studies with a quantitative description of the crowded nature of cytoplasm and of its local variations, to provide a direct readout of the impact of excluded volume on molecular assembly in living cells. Taken together, these studies will provide fundamental insights into the structural basis by which cells form biochemical compartments.

This proposal brings together two fields in biology, namely the emerging field of phase-separated assemblies in cell biology and state-of-the-art cellular cryo-electron tomography, to advance our understanding on a fundamental, yet illusive, question: the molecular organization of the cytoplasm.
Eukaryotes organize their biochemical reactions into functionally distinct compartments. Intriguingly, many, if not most, cellular compartments are not membrane enclosed. Rather, they assemble dynamically by phase separation, typically triggered upon a specific event. Despite significant progress on reconstituting such liquid-like assemblies in vitro, we lack information as to whether these compartments in vivo are indeed amorphous liquids, or whether they exhibit structural features such as gels or fibers. My recent work on sample preparation of cells for cryo-electron tomography, including cryo-focused ion beam thinning, guided by 3D correlative fluorescence microscopy, shows that we can now prepare site-specific ‘electron-transparent windows’ in suitable eukaryotic systems, which allow direct examination of structural features of cellular compartments in their cellular context. Here, we will use these techniques to elucidate the structural principles and cytoplasmic environment driving the dynamic assembly of two phase-separated compartments: Stress granules, which are RNA bodies that form rapidly in the cytoplasm upon cellular stress, and centrosomes, which are sites of microtubule nucleation. We will combine these studies with a quantitative description of the crowded nature of cytoplasm and of its local variations, to provide a direct readout of the impact of excluded volume on molecular assembly in living cells. Taken together, these studies will provide fundamental insights into the structural basis by which cells form biochemical compartments.

SummaryThe cell cortex is a highly dynamic layer of crosslinked actin filaments and myosin molecular motors beneath the cell membrane. It plays a central role in large scale rearrangements that occur inside cells. Many molecular mechanisms contribute to cortex structure and dynamics. However, cell scale physical properties of the cortex are difficult to grasp. This is problematic because for large scale rearrangements inside a cell, such as coherent flow of the cell cortex, it is the cell scale emergent properties that are important for the realization of such events. I will investigate how the actomyosin cytoskeleton behaves at a coarse grained and cellular scale, and will study how this emergent active behaviour is influenced by molecular mechanisms. We will study the cell cortex in the one cell stage C. elegans embryo, which undergoes large scale cortical flow during polarization and cytokinesis. We will combine theory and experiment. We will characterize cortex structure and dynamics with biophysical techniques such as cortical laser ablation and quantitative photobleaching experiments. We will develop and employ novel theoretical approaches to describe the cell scale mechanical behaviour in terms of an active complex fluid. We will utilize genetic approaches to understand how these emergent mechanical properties are influenced by molecular activities. A central goal is to arrive at a coarse grained description of the cortex that can predict future dynamic behaviour from the past structure, which is conceptually similar to how weather forecasting is accomplished. To date, systematic approaches to link molecular scale physical mechanisms to those on cellular scales are missing. This work will open new opportunities for cell biological and cell biophysical research, by providing a methodological approach for bridging scales, for studying emergent and large-scale active mechanical behaviours and linking them to molecular mechanisms.

The cell cortex is a highly dynamic layer of crosslinked actin filaments and myosin molecular motors beneath the cell membrane. It plays a central role in large scale rearrangements that occur inside cells. Many molecular mechanisms contribute to cortex structure and dynamics. However, cell scale physical properties of the cortex are difficult to grasp. This is problematic because for large scale rearrangements inside a cell, such as coherent flow of the cell cortex, it is the cell scale emergent properties that are important for the realization of such events. I will investigate how the actomyosin cytoskeleton behaves at a coarse grained and cellular scale, and will study how this emergent active behaviour is influenced by molecular mechanisms. We will study the cell cortex in the one cell stage C. elegans embryo, which undergoes large scale cortical flow during polarization and cytokinesis. We will combine theory and experiment. We will characterize cortex structure and dynamics with biophysical techniques such as cortical laser ablation and quantitative photobleaching experiments. We will develop and employ novel theoretical approaches to describe the cell scale mechanical behaviour in terms of an active complex fluid. We will utilize genetic approaches to understand how these emergent mechanical properties are influenced by molecular activities. A central goal is to arrive at a coarse grained description of the cortex that can predict future dynamic behaviour from the past structure, which is conceptually similar to how weather forecasting is accomplished. To date, systematic approaches to link molecular scale physical mechanisms to those on cellular scales are missing. This work will open new opportunities for cell biological and cell biophysical research, by providing a methodological approach for bridging scales, for studying emergent and large-scale active mechanical behaviours and linking them to molecular mechanisms.

Max ERC Funding

1 500 000 €

Duration

Start date: 2011-12-01, End date: 2017-08-31

Project acronymADAPTIVES

ProjectAlgorithmic Development and Analysis of Pioneer Techniques for Imaging with waVES

Researcher (PI)Chrysoula Tsogka

Host Institution (HI)IDRYMA TECHNOLOGIAS KAI EREVNAS

Call DetailsStarting Grant (StG), PE1, ERC-2009-StG

SummaryThe proposed work concerns the theoretical and numerical development of robust and adaptive methodologies for broadband imaging in clutter. The word clutter expresses our uncertainty on the wave speed of the propagation medium. Our results are expected to have a strong impact in a wide range of applications, including underwater acoustics, exploration geophysics and ultrasound non-destructive testing. Our machinery is coherent interferometry (CINT), a state-of-the-art statistically stable imaging methodology, highly suitable for the development of imaging methods in clutter. We aim to extend CINT along two complementary directions: novel types of applications, and further mathematical and numerical development so as to assess and extend its range of applicability. CINT is designed for imaging with partially coherent array data recorded in richly scattering media. It uses statistical smoothing techniques to obtain results that are independent of the clutter realization. Quantifying the amount of smoothing needed is difficult, especially when there is no a priori knowledge about the propagation medium. We intend to address this question by coupling the imaging process with the estimation of the medium's large scale features. Our algorithms rely on the residual coherence in the data. When the coherent signal is too weak, the CINT results are unsatisfactory. We propose two ways for enhancing the resolution of CINT: filter the data prior to imaging (noise reduction) and waveform design (optimize the source distribution). Finally, we propose to extend the applicability of our imaging-in-clutter methodologies by investigating the possibility of utilizing ambient noise sources to perform passive sensor imaging, as well as by studying the imaging problem in random waveguides.

The proposed work concerns the theoretical and numerical development of robust and adaptive methodologies for broadband imaging in clutter. The word clutter expresses our uncertainty on the wave speed of the propagation medium. Our results are expected to have a strong impact in a wide range of applications, including underwater acoustics, exploration geophysics and ultrasound non-destructive testing. Our machinery is coherent interferometry (CINT), a state-of-the-art statistically stable imaging methodology, highly suitable for the development of imaging methods in clutter. We aim to extend CINT along two complementary directions: novel types of applications, and further mathematical and numerical development so as to assess and extend its range of applicability. CINT is designed for imaging with partially coherent array data recorded in richly scattering media. It uses statistical smoothing techniques to obtain results that are independent of the clutter realization. Quantifying the amount of smoothing needed is difficult, especially when there is no a priori knowledge about the propagation medium. We intend to address this question by coupling the imaging process with the estimation of the medium's large scale features. Our algorithms rely on the residual coherence in the data. When the coherent signal is too weak, the CINT results are unsatisfactory. We propose two ways for enhancing the resolution of CINT: filter the data prior to imaging (noise reduction) and waveform design (optimize the source distribution). Finally, we propose to extend the applicability of our imaging-in-clutter methodologies by investigating the possibility of utilizing ambient noise sources to perform passive sensor imaging, as well as by studying the imaging problem in random waveguides.

SummaryAgeing is accompanied by ectopic white adipose tissue depositions in skeletal muscle and other anatomical locations, such as brown adipose tissue and the bone marrow. Ectopic fat accrual contributes to organ dysfunction, systemic insulin resistance, and other perturbations that have been implicated in metabolic diseases.
This research proposal aims to identify the regulatory cues that control the development of ectopic progenitor cells that give rise to this type of fat. It is hypothesized that an age-related dysfunction of the stem cell niche leads to an imbalance between (1) tissue-specific stem cells and (2) fibroblast-like, primarily adipogenic progenitors that reside within many tissues. Novel methodologies that assess stem/progenitor cell characteristics on the single cell level will be combined with animal models of lineage tracing to determine the developmental origin of these adipogenic progenitors and processes that regulate their function.
Notch signalling is a key signalling pathway that relies on direct physical interaction to control stem cell fate. It is proposed that impaired Notch activity contributes to the phenotypical shift of precursor cell distribution in aged tissues.
Lastly, the role of the stem cell niche in ectopic adipocyte progenitor formation will be analyzed. External signals originating from the surrounding niche cells regulate the developmental fate of stem cells. Secreted factors and their role in the formation of ectopic adipocyte precursors during senescence will be identified using a combination of biochemical and systems biology approaches.
Accomplishment of these studies will help to understand the basic processes of stem cell ageing and identify mechanisms of age-related functional decline in tissue regeneration. By targeting the population of tissue-resident adipogenic progenitor cells, therapeutic strategies could be developed to counteract metabolic complications associated with the ageing process.

Ageing is accompanied by ectopic white adipose tissue depositions in skeletal muscle and other anatomical locations, such as brown adipose tissue and the bone marrow. Ectopic fat accrual contributes to organ dysfunction, systemic insulin resistance, and other perturbations that have been implicated in metabolic diseases.
This research proposal aims to identify the regulatory cues that control the development of ectopic progenitor cells that give rise to this type of fat. It is hypothesized that an age-related dysfunction of the stem cell niche leads to an imbalance between (1) tissue-specific stem cells and (2) fibroblast-like, primarily adipogenic progenitors that reside within many tissues. Novel methodologies that assess stem/progenitor cell characteristics on the single cell level will be combined with animal models of lineage tracing to determine the developmental origin of these adipogenic progenitors and processes that regulate their function.
Notch signalling is a key signalling pathway that relies on direct physical interaction to control stem cell fate. It is proposed that impaired Notch activity contributes to the phenotypical shift of precursor cell distribution in aged tissues.
Lastly, the role of the stem cell niche in ectopic adipocyte progenitor formation will be analyzed. External signals originating from the surrounding niche cells regulate the developmental fate of stem cells. Secreted factors and their role in the formation of ectopic adipocyte precursors during senescence will be identified using a combination of biochemical and systems biology approaches.
Accomplishment of these studies will help to understand the basic processes of stem cell ageing and identify mechanisms of age-related functional decline in tissue regeneration. By targeting the population of tissue-resident adipogenic progenitor cells, therapeutic strategies could be developed to counteract metabolic complications associated with the ageing process.

Max ERC Funding

1 496 444 €

Duration

Start date: 2013-03-01, End date: 2018-02-28

Project acronymAIM2 INFLAMMASOME

ProjectCytosolic recognition of foreign nucleic acids: Molecular and functional characterization of AIM2, a central player in DNA-triggered inflammasome activation

Researcher (PI)Veit Hornung

Host Institution (HI)UNIVERSITAETSKLINIKUM BONN

Call DetailsStarting Grant (StG), LS6, ERC-2009-StG

SummaryHost cytokines, chemokines and type I IFNs are critical effectors of the innate immune response to viral and bacterial pathogens. Several classes of germ-line encoded pattern recognition receptors have been identified, which sense non-self nucleic acids and trigger these responses. Recently NLRP-3, a member of the NOD-like receptor (NLR) family, has been shown to sense endogenous danger signals, environmental insults and the DNA viruses adenovirus and HSV. Activation of NLRP-3 induces the formation of a large multiprotein complex in cells termed inflammasome , which controls the activity of pro-caspase-1 and the maturation of pro-IL-1² and pro-IL18 into their active forms. NLRP-3, however, does not regulate these responses to double stranded cytosolic DNA. We identified the cytosolic protein AIM2 as the missing receptor for cytosolic DNA. AIM2 contains a HIN200 domain, which binds to DNA and a pyrin domain, which associates with the adapter molecule ASC to activate both NF-ºB and caspase-1. Knock down of AIM2 down-regulates caspase-1-mediated IL-1² responses following DNA stimulation or vaccinia virus infection. Collectively, these observations demonstrate that AIM2 forms an inflammasome with the DNA ligand and ASC to activate caspase-1. Our underlying hypothesis for this proposal is that AIM2 plays a central role in host-defence to cytosolic microbial pathogens and also in DNA-triggered autoimmunity. The goals of this research proposal are to further characterize the DNA ligand for AIM2, to explore the molecular mechanisms of AIM2 activation, to define the contribution of AIM2 to host-defence against viral and bacterial pathogens and to assess its function in nucleic acid triggered autoimmune disease. The characterization of AIM2 and its role in innate immunity could open new avenues in the advancement of immunotherapy and treatment of autoimmune disease.

Host cytokines, chemokines and type I IFNs are critical effectors of the innate immune response to viral and bacterial pathogens. Several classes of germ-line encoded pattern recognition receptors have been identified, which sense non-self nucleic acids and trigger these responses. Recently NLRP-3, a member of the NOD-like receptor (NLR) family, has been shown to sense endogenous danger signals, environmental insults and the DNA viruses adenovirus and HSV. Activation of NLRP-3 induces the formation of a large multiprotein complex in cells termed inflammasome , which controls the activity of pro-caspase-1 and the maturation of pro-IL-1² and pro-IL18 into their active forms. NLRP-3, however, does not regulate these responses to double stranded cytosolic DNA. We identified the cytosolic protein AIM2 as the missing receptor for cytosolic DNA. AIM2 contains a HIN200 domain, which binds to DNA and a pyrin domain, which associates with the adapter molecule ASC to activate both NF-ºB and caspase-1. Knock down of AIM2 down-regulates caspase-1-mediated IL-1² responses following DNA stimulation or vaccinia virus infection. Collectively, these observations demonstrate that AIM2 forms an inflammasome with the DNA ligand and ASC to activate caspase-1. Our underlying hypothesis for this proposal is that AIM2 plays a central role in host-defence to cytosolic microbial pathogens and also in DNA-triggered autoimmunity. The goals of this research proposal are to further characterize the DNA ligand for AIM2, to explore the molecular mechanisms of AIM2 activation, to define the contribution of AIM2 to host-defence against viral and bacterial pathogens and to assess its function in nucleic acid triggered autoimmune disease. The characterization of AIM2 and its role in innate immunity could open new avenues in the advancement of immunotherapy and treatment of autoimmune disease.

Max ERC Funding

1 727 920 €

Duration

Start date: 2009-12-01, End date: 2014-11-30

Project acronymALLELECHOKER

ProjectDNA binding proteins for treatment of gain of function mutations

Researcher (PI)Enrico Maria Surace

Host Institution (HI)FONDAZIONE TELETHON

Call DetailsStarting Grant (StG), LS7, ERC-2012-StG_20111109

SummaryZinc finger (ZF) and transcription activator-like effector (TALE) based technologies are been allowing the tailored design of “artificial” DNA-binding proteins targeted to specific and unique DNA genomic sequences. Coupling DNA binding proteins to effectors domains enables the constitution of DNA binding factors for genomic directed transcriptional modulation or targeted genomic editing. We have demonstrated that pairing a ZF DNA binding protein to the transcriptional repressor Kruppel-associated box enables in vivo, the transcriptional repression of one of the most abundantly expressed gene in mammals, the human rhodopsin gene (RHO). We propose to generate RHO DNA binding silencers (“AlleleChoker”), which inactivate RHO either by transcriptional repression or targeted genome modification, irrespectively to wild-type or mutated alleles (mutational-independent approach), and combine RHO endogenous silencing to RHO replacement (silencing-replacement strategy). With this strategy in principle a single bimodal bio-therapeutic will enable the correction of any photoreceptor disease associated with RHO mutation. Adeno-associated viral (AAV) vector-based delivery will be used for photoreceptors gene transfer. Specifically our objectives are: 1) Construction of transcriptional repressors and nucleases for RHO silencing. Characterization and comparison of RHO silencing mediated by transcriptional repressors (ZFR/ TALER) or nucleases (ZFN/ TALEN) to generate genomic directed inactivation by non-homologous end-joining (NHEJ), and refer these results to RNA interference (RNAi) targeted to RHO; 2) RHO silencing in photoreceptors. to determine genome-wide DNA binding specificity of silencers, chromatin modifications and expression profile on human retinal explants; 3) Tuning silencing and replacement. To determine the impact of gene silencing-replacement strategy on disease progression in animal models of autosomal dominant retinitis pigmentosa (adRP) associated to RHO mutations

SummaryCurrently, more than 30% of all Europeans suffer from one or more allergic disorder but treatment is still mostly symptomatic due to a lack of understanding the underlying causality. Allergies are caused by type 2 immune responses triggered by recognition of harmless antigens. Both genetic and environmental factors have been proposed to favour allergic predisposition and both factors have a huge impact on the symbiotic microbiota and the intestinal immune system. Recently we and others showed that the transcription factor ROR(γt) seems to play a key role in mucosal tolerance in the gut and also regulates intestinal type 2 immune responses.
Based on these results I postulate two major events in the gut for the development of an allergy in the lifetime of an individual: First, a failure to establish mucosal tolerance or anergy constitutes a necessity for the outbreak of allergic symptoms and allergic disease. Second, a certain ‘core’ microbiome or pathway of the intestinal microbiota predispose certain individuals for the later development of allergic disorders. Therefore, I will address the following aims:
1) Influence of ROR(γt) on mucosal tolerance induction and allergic disorders
2) Elucidate the T cell receptor repertoire of intestinal Th2 and ROR(γt)+ Tregs and assess the role of alternative NFκB pathway for induction of mucosal tolerance
3) Identification of ‘core’ microbiome signatures or metabolic pathways that favour allergic predisposition
ALLERGUT will provide ground-breaking knowledge on molecular mechanisms of the failure of mucosal tolerance in the gut and will prove if the resident ROR(γt)+ T(reg) cells can function as a mechanistic starting point for molecular intervention strategies on the background of the hygiene hypothesis. The vision of ALLERGUT is to diagnose mucosal disbalance, prevent and treat allergic disorders even before outbreak and thereby promote Public Health initiative for better living.

Currently, more than 30% of all Europeans suffer from one or more allergic disorder but treatment is still mostly symptomatic due to a lack of understanding the underlying causality. Allergies are caused by type 2 immune responses triggered by recognition of harmless antigens. Both genetic and environmental factors have been proposed to favour allergic predisposition and both factors have a huge impact on the symbiotic microbiota and the intestinal immune system. Recently we and others showed that the transcription factor ROR(γt) seems to play a key role in mucosal tolerance in the gut and also regulates intestinal type 2 immune responses.
Based on these results I postulate two major events in the gut for the development of an allergy in the lifetime of an individual: First, a failure to establish mucosal tolerance or anergy constitutes a necessity for the outbreak of allergic symptoms and allergic disease. Second, a certain ‘core’ microbiome or pathway of the intestinal microbiota predispose certain individuals for the later development of allergic disorders. Therefore, I will address the following aims:
1) Influence of ROR(γt) on mucosal tolerance induction and allergic disorders
2) Elucidate the T cell receptor repertoire of intestinal Th2 and ROR(γt)+ Tregs and assess the role of alternative NFκB pathway for induction of mucosal tolerance
3) Identification of ‘core’ microbiome signatures or metabolic pathways that favour allergic predisposition
ALLERGUT will provide ground-breaking knowledge on molecular mechanisms of the failure of mucosal tolerance in the gut and will prove if the resident ROR(γt)+ T(reg) cells can function as a mechanistic starting point for molecular intervention strategies on the background of the hygiene hypothesis. The vision of ALLERGUT is to diagnose mucosal disbalance, prevent and treat allergic disorders even before outbreak and thereby promote Public Health initiative for better living.

SummaryBlood and lymphatic vessels have been the subject of intense investigation due to their important role in cancer development and in cardiovascular diseases. The significant advance in the methods used to modify and analyse gene function have allowed us to obtain a much better understanding of the molecular mechanisms involved in the regulation of the biology of blood vessels. However, there are two key aspects that significantly diminish our capacity to understand the function of gene networks and their intersections in vivo. One is the long time that is usually required to generate a given double mutant vertebrate tissue, and the other is the lack of single-cell genetic and phenotypic resolution. We have recently performed an in vivo comparative transcriptome analysis of highly angiogenic endothelial cells experiencing different VEGF and Notch signalling levels. These are two of the most important molecular mechanisms required for the adequate differentiation, proliferation and sprouting of endothelial cells. Using the information generated from this analysis, the overall aim of the proposed project is to characterize the vascular function of some of the previously identified genes and determine how they functionally interact with these two signalling pathways. We propose to use novel inducible genetic tools that will allow us to generate a spatially and temporally regulated fluorescent cell mosaic matrix for quantitative analysis. This will enable us to analyse with unprecedented speed and resolution the function of several different genes simultaneously, during vascular development, homeostasis or associated diseases. Understanding the genetic epistatic interactions that control the differentiation and behaviour of endothelial cells, in different contexts, and with high cellular definition, has the potential to unveil new mechanisms with high biological and therapeutic relevance.

Blood and lymphatic vessels have been the subject of intense investigation due to their important role in cancer development and in cardiovascular diseases. The significant advance in the methods used to modify and analyse gene function have allowed us to obtain a much better understanding of the molecular mechanisms involved in the regulation of the biology of blood vessels. However, there are two key aspects that significantly diminish our capacity to understand the function of gene networks and their intersections in vivo. One is the long time that is usually required to generate a given double mutant vertebrate tissue, and the other is the lack of single-cell genetic and phenotypic resolution. We have recently performed an in vivo comparative transcriptome analysis of highly angiogenic endothelial cells experiencing different VEGF and Notch signalling levels. These are two of the most important molecular mechanisms required for the adequate differentiation, proliferation and sprouting of endothelial cells. Using the information generated from this analysis, the overall aim of the proposed project is to characterize the vascular function of some of the previously identified genes and determine how they functionally interact with these two signalling pathways. We propose to use novel inducible genetic tools that will allow us to generate a spatially and temporally regulated fluorescent cell mosaic matrix for quantitative analysis. This will enable us to analyse with unprecedented speed and resolution the function of several different genes simultaneously, during vascular development, homeostasis or associated diseases. Understanding the genetic epistatic interactions that control the differentiation and behaviour of endothelial cells, in different contexts, and with high cellular definition, has the potential to unveil new mechanisms with high biological and therapeutic relevance.

Summary"Blood vessels pervade all tissues in the body to supply nutrients and oxygen. Aberrant vessel growth and function are hallmarks of cancer and cardiovascular diseases and they contribute to disease pathogenesis. Antiangiogenic therapeutics have reached the clinic, but limited efficacy and resistance raise unresolved challenges. The current limitations of angiogenic medicine call for a more integrated understanding of the angiogenic process that focuses not only on the instigators of vessel branching but also on mechanisms that sustain vessel growth. Recent insights into fundamental aspects of cell growth move metabolism into spotlight and establish how proliferating cells reprogram their metabolism to provide energy and building blocks for cell replication. During angiogenesis, endothelial cells (ECs) also convert between growth states: although mostly quiescent in adult tissues, ECs divide and migrate rapidly upon angiogenic stimulation. To allow growth of new vessel branches, ECs therefore need to adjust their metabolism to increase energy production and biosynthetic activity. However, the molecular mechanisms that coordinate EC metabolism with angiogenic signalling are not known to date. In this proposal, we put forth the hypothesis that metabolic regulation is a key component of the endothelial angiogenic machinery that is required to sustain vessel growth. Thus, this proposal aims (I) to define transcriptional circuits that link EC growth with metabolism, (II) to explore the regulation of these transcriptional networks by lysine acetylation, a nutrient-regulated protein modification with key functions in metabolism, and (III) to assess the role of sirtuin deacetylases for sensing endothelial energetics during vascular growth. Understanding the principles of angiogenesis-metabolism crosstalk will not only yield novel insights into the basic mechanisms of vessel formation but will also provide unprecedented opportunities for future drug development."

"Blood vessels pervade all tissues in the body to supply nutrients and oxygen. Aberrant vessel growth and function are hallmarks of cancer and cardiovascular diseases and they contribute to disease pathogenesis. Antiangiogenic therapeutics have reached the clinic, but limited efficacy and resistance raise unresolved challenges. The current limitations of angiogenic medicine call for a more integrated understanding of the angiogenic process that focuses not only on the instigators of vessel branching but also on mechanisms that sustain vessel growth. Recent insights into fundamental aspects of cell growth move metabolism into spotlight and establish how proliferating cells reprogram their metabolism to provide energy and building blocks for cell replication. During angiogenesis, endothelial cells (ECs) also convert between growth states: although mostly quiescent in adult tissues, ECs divide and migrate rapidly upon angiogenic stimulation. To allow growth of new vessel branches, ECs therefore need to adjust their metabolism to increase energy production and biosynthetic activity. However, the molecular mechanisms that coordinate EC metabolism with angiogenic signalling are not known to date. In this proposal, we put forth the hypothesis that metabolic regulation is a key component of the endothelial angiogenic machinery that is required to sustain vessel growth. Thus, this proposal aims (I) to define transcriptional circuits that link EC growth with metabolism, (II) to explore the regulation of these transcriptional networks by lysine acetylation, a nutrient-regulated protein modification with key functions in metabolism, and (III) to assess the role of sirtuin deacetylases for sensing endothelial energetics during vascular growth. Understanding the principles of angiogenesis-metabolism crosstalk will not only yield novel insights into the basic mechanisms of vessel formation but will also provide unprecedented opportunities for future drug development."

SummaryNormal placental angiogenesis is critical for embryonic survival and development. Epigenetic modifications, such as methylation of CpG islands, regulate the expression and imprinting of genes. Epigenetic abnormalities have been observed in embryos from assisted reproductive technologies (ART), which could explain the poor placental vascularisation, embryonic/fetal death, and altered fetal growth in these pregnancies. Both cloned (somatic cell nuclear transfer, or SNCT) and monoparental (parthogenotes, only maternal genes; androgenotes, only paternal genes) embryos provide important models for studying defects in expression and methylation status/imprinting of genes regulating placental function. Our hypothesis is that placental vascular development is compromised during early pregnancy in embryos from ART, in part due to altered expression or imprinting/methylation status of specific genes regulating placental angiogenesis. We will evaluate fetal growth, placental vascular growth, and expression and epigenetic status of genes regulating placental angiogenesis during early pregnancy in 3 Specific Aims: (1) after natural mating; (2) after transfer of biparental embryos from in vitro fertilization, and SCNT; and (3) after transfer of parthenogenetic or androgenetic embryos. These studies will therefore contribute substantially to our understanding of the regulation of placental development and vascularisation during early pregnancy, and could pinpoint the mechanism contributing to embryonic loss and developmental abnormalities in foetuses from ART. Any or all of these observations will contribute to our understanding of and also our ability to successfully employ ART, which are becoming very wide spread and important in human medicine as well as in animal production.

Normal placental angiogenesis is critical for embryonic survival and development. Epigenetic modifications, such as methylation of CpG islands, regulate the expression and imprinting of genes. Epigenetic abnormalities have been observed in embryos from assisted reproductive technologies (ART), which could explain the poor placental vascularisation, embryonic/fetal death, and altered fetal growth in these pregnancies. Both cloned (somatic cell nuclear transfer, or SNCT) and monoparental (parthogenotes, only maternal genes; androgenotes, only paternal genes) embryos provide important models for studying defects in expression and methylation status/imprinting of genes regulating placental function. Our hypothesis is that placental vascular development is compromised during early pregnancy in embryos from ART, in part due to altered expression or imprinting/methylation status of specific genes regulating placental angiogenesis. We will evaluate fetal growth, placental vascular growth, and expression and epigenetic status of genes regulating placental angiogenesis during early pregnancy in 3 Specific Aims: (1) after natural mating; (2) after transfer of biparental embryos from in vitro fertilization, and SCNT; and (3) after transfer of parthenogenetic or androgenetic embryos. These studies will therefore contribute substantially to our understanding of the regulation of placental development and vascularisation during early pregnancy, and could pinpoint the mechanism contributing to embryonic loss and developmental abnormalities in foetuses from ART. Any or all of these observations will contribute to our understanding of and also our ability to successfully employ ART, which are becoming very wide spread and important in human medicine as well as in animal production.

SummaryAtherosclerosis is a chronic immune disease of arteries that causes vessel-narrowing atherosclerotic plaques. Its acute complications, myocardial infarction and stroke, are the leading causes of death worldwide. Atherosclerosis is accompanied by an inflammatory and autoimmune response with CD4+ T-helper cells that recognize self-antigens, including ApoB-100 (ApoB), the main protein in low-density lipoprotein (LDL) cholesterol. Although their existence has been inferred from indirect evidence, the existence and function of atherosclerosis-specific, self-reactive CD4+ T cells on a single-cell level remains elusive. In particular, it is unclear whether these are pro- or anti-inflammatory.
Preliminary data suggest the existence of a natural pool of ApoB-reactive T-helper cells that share properties with atheroprotective T-regulatory cells but transform into pathogenic T-effector cells in the natural course of disease. This proposal aims to explore this loss of protective immunity on a cellular and function level. It employs novel tools to detect antigen-specific T cells in vivo by MHC-II multimers, mass cytometry (CyTOF), single cell RNA-sequencing (scRNA-seq), lineage-tracing mouse models, and live cell imaging. Based on the anticipated findings, this study will define a map of auto-reactive T-helper cell phenotypes in a temporal, spatial, and functional dimension. These insights will be used to identify novel immunomodulatory strategies to therapeutically stabilize the population of protective ApoB-specific T-helper cells, or to prevent their transformation into pathogenic T cell phenotypes by adoptive cells transfers, vaccination, or cytokine-blockade. In clinical association studies, a direct correlation of auto-immunity and clinical atherosclerosis will be tested.
This proposal will decipher traits of protective immunity in atherosclerosis and help to build the conceptual framework to define novel therapeutic strategies for patients.

Atherosclerosis is a chronic immune disease of arteries that causes vessel-narrowing atherosclerotic plaques. Its acute complications, myocardial infarction and stroke, are the leading causes of death worldwide. Atherosclerosis is accompanied by an inflammatory and autoimmune response with CD4+ T-helper cells that recognize self-antigens, including ApoB-100 (ApoB), the main protein in low-density lipoprotein (LDL) cholesterol. Although their existence has been inferred from indirect evidence, the existence and function of atherosclerosis-specific, self-reactive CD4+ T cells on a single-cell level remains elusive. In particular, it is unclear whether these are pro- or anti-inflammatory.
Preliminary data suggest the existence of a natural pool of ApoB-reactive T-helper cells that share properties with atheroprotective T-regulatory cells but transform into pathogenic T-effector cells in the natural course of disease. This proposal aims to explore this loss of protective immunity on a cellular and function level. It employs novel tools to detect antigen-specific T cells in vivo by MHC-II multimers, mass cytometry (CyTOF), single cell RNA-sequencing (scRNA-seq), lineage-tracing mouse models, and live cell imaging. Based on the anticipated findings, this study will define a map of auto-reactive T-helper cell phenotypes in a temporal, spatial, and functional dimension. These insights will be used to identify novel immunomodulatory strategies to therapeutically stabilize the population of protective ApoB-specific T-helper cells, or to prevent their transformation into pathogenic T cell phenotypes by adoptive cells transfers, vaccination, or cytokine-blockade. In clinical association studies, a direct correlation of auto-immunity and clinical atherosclerosis will be tested.
This proposal will decipher traits of protective immunity in atherosclerosis and help to build the conceptual framework to define novel therapeutic strategies for patients.

Max ERC Funding

1 499 946 €

Duration

Start date: 2020-01-01, End date: 2024-12-31

Project acronymANOPTSETCON

ProjectAnalysis of optimal sets and optimal constants: old questions and new results

SummaryThe analysis of geometric and functional inequalities naturally leads to consider the extremal cases, thus
looking for optimal sets, or optimal functions, or optimal constants. The most classical examples are the (different versions of the) isoperimetric inequality and the Sobolev-like inequalities. Much is known about equality cases and best constants, but there are still many questions which seem quite natural but yet have no answer. For instance, it is not known, even in the 2-dimensional space, the answer of a question by Brezis: which set,
among those with a given volume, has the biggest Sobolev-Poincaré constant for p=1? This is a very natural problem, and it appears reasonable that the optimal set should be the ball, but this has never been proved. The interest in problems like this relies not only in the extreme simplicity of the questions and in their classical flavour, but also in the new ideas and techniques which are needed to provide the answers.
The main techniques that we aim to use are fine arguments of symmetrization, geometric constructions and tools from mass transportation (which is well known to be deeply connected with functional inequalities). These are the basic tools that we already used to reach, in last years, many results in a specific direction, namely the search of sharp quantitative inequalities. Our first result, together with Fusco and Maggi, showed what follows. Everybody knows that the set which minimizes the perimeter with given volume is the ball.
But is it true that a set which almost minimizes the perimeter must be close to a ball? The question had been posed in the 1920's and many partial result appeared in the years. In our paper (Ann. of Math., 2007) we proved the sharp result. Many other results of this kind were obtained in last two years.

The analysis of geometric and functional inequalities naturally leads to consider the extremal cases, thus
looking for optimal sets, or optimal functions, or optimal constants. The most classical examples are the (different versions of the) isoperimetric inequality and the Sobolev-like inequalities. Much is known about equality cases and best constants, but there are still many questions which seem quite natural but yet have no answer. For instance, it is not known, even in the 2-dimensional space, the answer of a question by Brezis: which set,
among those with a given volume, has the biggest Sobolev-Poincaré constant for p=1? This is a very natural problem, and it appears reasonable that the optimal set should be the ball, but this has never been proved. The interest in problems like this relies not only in the extreme simplicity of the questions and in their classical flavour, but also in the new ideas and techniques which are needed to provide the answers.
The main techniques that we aim to use are fine arguments of symmetrization, geometric constructions and tools from mass transportation (which is well known to be deeply connected with functional inequalities). These are the basic tools that we already used to reach, in last years, many results in a specific direction, namely the search of sharp quantitative inequalities. Our first result, together with Fusco and Maggi, showed what follows. Everybody knows that the set which minimizes the perimeter with given volume is the ball.
But is it true that a set which almost minimizes the perimeter must be close to a ball? The question had been posed in the 1920's and many partial result appeared in the years. In our paper (Ann. of Math., 2007) we proved the sharp result. Many other results of this kind were obtained in last two years.

Max ERC Funding

540 000 €

Duration

Start date: 2010-08-01, End date: 2015-07-31

Project acronymANOREP

ProjectTargeting the reproductive biology of the malaria mosquito Anopheles gambiae: from laboratory studies to field applications

Researcher (PI)Flaminia Catteruccia

Host Institution (HI)UNIVERSITA DEGLI STUDI DI PERUGIA

Call DetailsStarting Grant (StG), LS2, ERC-2010-StG_20091118

SummaryAnopheles gambiae mosquitoes are the major vectors of malaria, a disease with devastating consequences for
human health. Novel methods for controlling the natural vector populations are urgently needed, given the
evolution of insecticide resistance in mosquitoes and the lack of novel insecticidals. Understanding the
processes at the bases of mosquito biology may help to roll back malaria. In this proposal, we will target
mosquito reproduction, a major determinant of the An. gambiae vectorial capacity. This will be achieved at
two levels: (i) fundamental research, to provide a deeper knowledge of the processes regulating reproduction
in this species, and (ii) applied research, to identify novel targets and to develop innovative approaches for
the control of natural populations. We will focus our analysis on three major players of mosquito
reproduction: male accessory glands (MAGs), sperm, and spermatheca, in both laboratory and field settings.
We will then translate this information into the identification of inhibitors of mosquito fertility. The
experimental activities will be divided across three objectives. In Objective 1, we will unravel the role of the
MAGs in shaping mosquito fertility and behaviour, by performing a combination of transcriptional and
functional studies that will reveal the multifaceted activities of these tissues. In Objective 2 we will instead
focus on the identification of the male and female factors responsible for sperm viability and function.
Results obtained in both objectives will be validated in field mosquitoes. In Objective 3, we will perform
screens aimed at the identification of inhibitors of mosquito reproductive success. This study will reveal as
yet unknown molecular mechanisms underlying reproductive success in mosquitoes, considerably increasing
our knowledge beyond the state-of-the-art and critically contributing with innovative tools and ideas to the
fight against malaria.

Anopheles gambiae mosquitoes are the major vectors of malaria, a disease with devastating consequences for
human health. Novel methods for controlling the natural vector populations are urgently needed, given the
evolution of insecticide resistance in mosquitoes and the lack of novel insecticidals. Understanding the
processes at the bases of mosquito biology may help to roll back malaria. In this proposal, we will target
mosquito reproduction, a major determinant of the An. gambiae vectorial capacity. This will be achieved at
two levels: (i) fundamental research, to provide a deeper knowledge of the processes regulating reproduction
in this species, and (ii) applied research, to identify novel targets and to develop innovative approaches for
the control of natural populations. We will focus our analysis on three major players of mosquito
reproduction: male accessory glands (MAGs), sperm, and spermatheca, in both laboratory and field settings.
We will then translate this information into the identification of inhibitors of mosquito fertility. The
experimental activities will be divided across three objectives. In Objective 1, we will unravel the role of the
MAGs in shaping mosquito fertility and behaviour, by performing a combination of transcriptional and
functional studies that will reveal the multifaceted activities of these tissues. In Objective 2 we will instead
focus on the identification of the male and female factors responsible for sperm viability and function.
Results obtained in both objectives will be validated in field mosquitoes. In Objective 3, we will perform
screens aimed at the identification of inhibitors of mosquito reproductive success. This study will reveal as
yet unknown molecular mechanisms underlying reproductive success in mosquitoes, considerably increasing
our knowledge beyond the state-of-the-art and critically contributing with innovative tools and ideas to the
fight against malaria.

SummaryThis is a proposal for research at the interface of analytic number theory, automorphic forms and algebraic geometry. Motivated by fundamental conjectures in number theory, classical problems will be investigated in higher order situations: general number fields, automorphic forms on higher rank groups, the arithmetic of algebraic varieties of higher degree. In particular, I want to focus on
- computation of moments of L-function of degree 3 and higher with applications to subconvexity and/or non-vanishing, as well as subconvexity for multiple L-functions;
- bounds for sup-norms of cusp forms on various spaces and equidistribution of Hecke correspondences;
- automorphic forms on higher rank groups and general number fields, in particular new bounds towards the Ramanujan conjecture;
- a proof of Manin's conjecture for a certain class of singular algebraic varieties.
The underlying methods are closely related; for example, rational points on algebraic varieties
will be counted by a multiple L-series technique.

This is a proposal for research at the interface of analytic number theory, automorphic forms and algebraic geometry. Motivated by fundamental conjectures in number theory, classical problems will be investigated in higher order situations: general number fields, automorphic forms on higher rank groups, the arithmetic of algebraic varieties of higher degree. In particular, I want to focus on
- computation of moments of L-function of degree 3 and higher with applications to subconvexity and/or non-vanishing, as well as subconvexity for multiple L-functions;
- bounds for sup-norms of cusp forms on various spaces and equidistribution of Hecke correspondences;
- automorphic forms on higher rank groups and general number fields, in particular new bounds towards the Ramanujan conjecture;
- a proof of Manin's conjecture for a certain class of singular algebraic varieties.
The underlying methods are closely related; for example, rational points on algebraic varieties
will be counted by a multiple L-series technique.

SummaryHere we propose a first step toward a direct reconstruction of the evolutionary history of human infectious disease agents by obtaining genome wide data of historic pathogens. Through an extensive screening of skeletal collections from well-characterized catastrophe, or emergency, mass burials we plan to detect and sequence pathogen DNA from various historic pandemics spanning at least 2,500 years using a general purpose molecular capture method that will screen for hundreds of pathogens in a single assay. Subsequent experiments will attempt to reconstruct full genomes from all pathogenic species identified. The molecular fossil record of human pathogens will provide insights into host adaptation and evolutionary rates of infectious disease. In addition, human genomic regions relating to disease susceptibility and immunity will be characterized in the skeletal material in order to observe the direct effect that pathogens have made on the genetic makeup of human populations over time. The results of this project will allow a multidisciplinary interpretation of historical pandemics that have influenced the course of human history. It will provide priceless information for the field of history, evolutionary biology, anthropology as well as medicine and will have direct consequences on how we manage emerging and re-emerging infectious disease in the future.

Here we propose a first step toward a direct reconstruction of the evolutionary history of human infectious disease agents by obtaining genome wide data of historic pathogens. Through an extensive screening of skeletal collections from well-characterized catastrophe, or emergency, mass burials we plan to detect and sequence pathogen DNA from various historic pandemics spanning at least 2,500 years using a general purpose molecular capture method that will screen for hundreds of pathogens in a single assay. Subsequent experiments will attempt to reconstruct full genomes from all pathogenic species identified. The molecular fossil record of human pathogens will provide insights into host adaptation and evolutionary rates of infectious disease. In addition, human genomic regions relating to disease susceptibility and immunity will be characterized in the skeletal material in order to observe the direct effect that pathogens have made on the genetic makeup of human populations over time. The results of this project will allow a multidisciplinary interpretation of historical pandemics that have influenced the course of human history. It will provide priceless information for the field of history, evolutionary biology, anthropology as well as medicine and will have direct consequences on how we manage emerging and re-emerging infectious disease in the future.

SummaryDeregulated apoptotic signaling in hematopoietic stem and progenitor cells (HSPCs) strongly contributes to the pathogenesis and phenotypes of congenital bone marrow failure and myelodysplastic syndromes (MDS) and their progression to acute myeloid leukemia (AML). HSPCs are highly susceptible to apoptosis during bone marrow failure and early MDS, but AML evolution selects for apoptosis resistance. Little is known about the main apoptotic players and their regulators. ApoptoMDS will investigate the impact of apoptotic deregulation for pathogenesis, correlate apoptotic susceptibility with the kinetics of disease progression and characterize the mechanism by which apoptotic susceptibility turns into resistance. ApoptoMDS will draw on a large collection of patient-derived samples and genetically engineered mouse models to investigate disease progression in serially transplanted and xenotransplanted mice. How activated DNA damage checkpoint signaling contributes to syndrome phenotypes and HSPC hypersusceptibility to apoptosis will be assessed. Checkpoint activation confers a competitive disadvantage, and HSPCs undergoing malignant transformation are under high selective pressure to inactivate it. Checkpoint abrogation mitigates the hematological phenotype, but increases the risk of AML evolution. ApoptoMDS aims to analyze if inhibiting apoptosis in HSPCs from bone marrow failure and early-stage MDS can overcome the dilemma of checkpoint abrogation. Whether inhibiting apoptosis is sufficient to improve HSPC function will be tested on several levels and validated in patient-derived samples. How inhibiting apoptosis in the presence of functional checkpoint signaling influences malignant transformation kinetics will be assessed. If, as hypothesized, inhibiting apoptosis both mitigates hematological symptoms and delays AML evolution, ApoptoMDS will pave the way for novel therapeutic approaches to expand the less severe symptomatic period for patients with these syndromes.

Deregulated apoptotic signaling in hematopoietic stem and progenitor cells (HSPCs) strongly contributes to the pathogenesis and phenotypes of congenital bone marrow failure and myelodysplastic syndromes (MDS) and their progression to acute myeloid leukemia (AML). HSPCs are highly susceptible to apoptosis during bone marrow failure and early MDS, but AML evolution selects for apoptosis resistance. Little is known about the main apoptotic players and their regulators. ApoptoMDS will investigate the impact of apoptotic deregulation for pathogenesis, correlate apoptotic susceptibility with the kinetics of disease progression and characterize the mechanism by which apoptotic susceptibility turns into resistance. ApoptoMDS will draw on a large collection of patient-derived samples and genetically engineered mouse models to investigate disease progression in serially transplanted and xenotransplanted mice. How activated DNA damage checkpoint signaling contributes to syndrome phenotypes and HSPC hypersusceptibility to apoptosis will be assessed. Checkpoint activation confers a competitive disadvantage, and HSPCs undergoing malignant transformation are under high selective pressure to inactivate it. Checkpoint abrogation mitigates the hematological phenotype, but increases the risk of AML evolution. ApoptoMDS aims to analyze if inhibiting apoptosis in HSPCs from bone marrow failure and early-stage MDS can overcome the dilemma of checkpoint abrogation. Whether inhibiting apoptosis is sufficient to improve HSPC function will be tested on several levels and validated in patient-derived samples. How inhibiting apoptosis in the presence of functional checkpoint signaling influences malignant transformation kinetics will be assessed. If, as hypothesized, inhibiting apoptosis both mitigates hematological symptoms and delays AML evolution, ApoptoMDS will pave the way for novel therapeutic approaches to expand the less severe symptomatic period for patients with these syndromes.

SummaryThe proteins of the Bcl-2 family function as key regulators of apoptosis by controlling the permeabilization of the mitochondrial outer membrane. They form an intricate, fine-tuned interaction network which is altered in cancer cells to avoid cell death. Currently, we do not understand how signaling within this network, which combines events in cytosol and membranes, is orchestrated to decide the cell fate. The main goal of this proposal is to unravel how apoptosis signaling is integrated by the Bcl-2 network by determining the quantitative Bcl-2 interactome and building with it a mathematical model that identifies which interactions determine the overall outcome. To this aim, we have established a reconstituted system for the quantification of the interactions between Bcl-2 proteins not only in solution but also in membranes at the single molecule level by fluorescence correlation spectroscopy (FCS).
(1) This project aims to quantify the relative affinities between an reconstituted Bcl-2 network by FCS.
(2) This will be combined with quantitative studies in living cells, which include the signaling pathway in its entirety. To this aim, we will develop new FCS methods for mitochondria.
(3) The structural and dynamic aspects of the Bcl-2 network will be studied by super resolution and live cell microscopy.
(4) The acquired knowledge will be used to build a mathematical model that uncovers how the multiple interactions within the Bcl-2 network are integrated and identifies critical steps in apoptosis regulation.
These studies are expected to broaden the general knowledge about the design principles of cellular signaling as well as how cancer cells alter the Bcl-2 network to escape cell death. This systems analysis will allow us to predict which perturbations in the Bcl-2 network of cancer cells can switch signaling towards cell death. Ultimately it could be translated into clinical applications for anticancer therapy.

The proteins of the Bcl-2 family function as key regulators of apoptosis by controlling the permeabilization of the mitochondrial outer membrane. They form an intricate, fine-tuned interaction network which is altered in cancer cells to avoid cell death. Currently, we do not understand how signaling within this network, which combines events in cytosol and membranes, is orchestrated to decide the cell fate. The main goal of this proposal is to unravel how apoptosis signaling is integrated by the Bcl-2 network by determining the quantitative Bcl-2 interactome and building with it a mathematical model that identifies which interactions determine the overall outcome. To this aim, we have established a reconstituted system for the quantification of the interactions between Bcl-2 proteins not only in solution but also in membranes at the single molecule level by fluorescence correlation spectroscopy (FCS).
(1) This project aims to quantify the relative affinities between an reconstituted Bcl-2 network by FCS.
(2) This will be combined with quantitative studies in living cells, which include the signaling pathway in its entirety. To this aim, we will develop new FCS methods for mitochondria.
(3) The structural and dynamic aspects of the Bcl-2 network will be studied by super resolution and live cell microscopy.
(4) The acquired knowledge will be used to build a mathematical model that uncovers how the multiple interactions within the Bcl-2 network are integrated and identifies critical steps in apoptosis regulation.
These studies are expected to broaden the general knowledge about the design principles of cellular signaling as well as how cancer cells alter the Bcl-2 network to escape cell death. This systems analysis will allow us to predict which perturbations in the Bcl-2 network of cancer cells can switch signaling towards cell death. Ultimately it could be translated into clinical applications for anticancer therapy.

Max ERC Funding

1 462 900 €

Duration

Start date: 2013-04-01, End date: 2019-03-31

Project acronymAppSAM

ProjectA Flexible Platform for the Application of SAM-dependent enzymes

Researcher (PI)Jennifer Nina ANDEXER

Host Institution (HI)ALBERT-LUDWIGS-UNIVERSITAET FREIBURG

Call DetailsStarting Grant (StG), LS9, ERC-2016-STG

SummaryAppSAM will unlock the synthetic capability of S-adenosyl¬methionine (SAM)-dependent methyltransferases and radical SAM enzymes for application in environmentally friendly and fully sustainable reactions. The biotechnological application of these enzymes will provide access to chemo-, regio- and stereoselective methylations and alkylations, as well as to a wide range of complex rearrangement reactions that are currently not possible through traditional approaches. Methylation reactions are of particular interest due to their importance in epigenetics, cancer metabolism and the development of novel pharmaceuticals. As chemical methylation methods often involve toxic compounds and rarely exhibit the desired selectivity and specificity, there is an urgent need for new, environmentally friendly methodologies.
The proposed project will meet these demands by the provision of modular in vitro and in vivo systems that can be tailored to specific applications. In the first phase of AppSAM, efficient in vitro SAM-regeneration systems will be developed for use with methyltransferases as well as radical SAM enzymes. To achieve this aim, enzymes from different biosynthetic pathways will be combined in multi-enzyme cascades; methods from enzyme and reaction engineering will be used for optimisation. The second phase of AppSAM will address the application on a preparative scale. This will include the isolation of pure product from the in vitro systems, reactions using immobilised enzymes and extracts from in vivo productions. In addition to E. coli, the methylotrophic bacterium Methylobacter extorquens AM1 will be used as a host for the in vivo systems. M. extorquens can use C1 building blocks such as methanol as the sole carbon source, thereby initiating the biotechnological methylation process from a green source material and making the process fully sustainable, as well as being compatible with an envisaged “methanol economy”.

AppSAM will unlock the synthetic capability of S-adenosyl¬methionine (SAM)-dependent methyltransferases and radical SAM enzymes for application in environmentally friendly and fully sustainable reactions. The biotechnological application of these enzymes will provide access to chemo-, regio- and stereoselective methylations and alkylations, as well as to a wide range of complex rearrangement reactions that are currently not possible through traditional approaches. Methylation reactions are of particular interest due to their importance in epigenetics, cancer metabolism and the development of novel pharmaceuticals. As chemical methylation methods often involve toxic compounds and rarely exhibit the desired selectivity and specificity, there is an urgent need for new, environmentally friendly methodologies.
The proposed project will meet these demands by the provision of modular in vitro and in vivo systems that can be tailored to specific applications. In the first phase of AppSAM, efficient in vitro SAM-regeneration systems will be developed for use with methyltransferases as well as radical SAM enzymes. To achieve this aim, enzymes from different biosynthetic pathways will be combined in multi-enzyme cascades; methods from enzyme and reaction engineering will be used for optimisation. The second phase of AppSAM will address the application on a preparative scale. This will include the isolation of pure product from the in vitro systems, reactions using immobilised enzymes and extracts from in vivo productions. In addition to E. coli, the methylotrophic bacterium Methylobacter extorquens AM1 will be used as a host for the in vivo systems. M. extorquens can use C1 building blocks such as methanol as the sole carbon source, thereby initiating the biotechnological methylation process from a green source material and making the process fully sustainable, as well as being compatible with an envisaged “methanol economy”.